1. Field of the Invention
This invention relates to an improved device for the purification of drinking water and methods for using the same. The improvement in the device comprises the addition of certain inhibitors to the purification agent contained in the device to substantially inhibit the migration of the fine particles of the purification agent through the porous member of the container. The primary intended use of the device is for the treatment of tap water or other similar sources of drinking water to substantially remove impurities that may have eluded conventional and customary water treatment practices. The effect of these impurities, depending upon an individual's discriminatory ability, detract from the organoleptic acceptability of the water, and in some cases may present a potential risk to health.
Water intended for human consumption is usually derived from sources that have been exposed to various sources of human and industrial wastes and is therefor treated to render it fit for human consumption prior to its being piped into the home. Generally, water that reaches the treatment plant is treated with chlorine to control bacteria. Sediment in the water, mud, other solids, sewage, etc., that is heavy enough to settle to the bottom of the sediment basins, does so. Numerous chemicals are added to the water to encourage small particles to clump together, adjust the pH, control odor and further inhibit bacteria build-up. Despite this processing, some of the impurities and toxic materials are never removed from the water before reaching the consumer. In fact, the chlorination treatment itself is suspected of further contributing to the problem by the chlorination of organics in the water to form halocarbons.
While it is well known that further treatment of the water with granular activated carbon has the ability to remove many of the objectionable materials, many towns and even some major cities find such further treatment too expensive.
2. State of the Art
Persons sensitized to this problem have generally had two options open to them. The simplest, but perhaps the most costly to the individual choosing this option, is the purchase of bottled "pure water" from various sources. Unfortunately, these waters are marketed at a rather substantial price considering the price of most municipally supplied waters. The second alternative is the installation of complicated and costly devices to condition the water once it reaches the home. Unfortunately in many cases, these devices overcondition the water and remove essential minerals needed in key body processes; moreover, they require significant maintenance. Various devices have been disclosed for treating water with ion exchange resins or other deionizing substances.
Edelestein, U.S. Pat. No. 1,504,329 discloses an apparatus for base exchanging substances and relates to water softeners of the base exchanging silicate class and to methods of using them. This patent does not contemplate the use of granular activated carbon nor does it direct itself to the inhibition of migration of particulate matter from the described device. Gudmundsen, U.S. Pat. No. 2,202,001, discloses another water softener device and consists of a porous spherical cloth bag containing a base exchanging material and having an opening for the addition of the water to be treated. The water, once treated, exits the bag by passing through the porous side walls of the bag. Nothing is disclosed concerning the inhibition of migration of particulate matter through the aforementioned side walls. Eweson, U.S. Pat. No. 2,335,657, discloses a hand operated water softening apparatus employing zeolite or other granular materials for softening small batches of water. Ellison, U.S. Pat. No. 2,759,307, discloses a unit for treating water to remove undesirable ions consisting of an ion exchange substance contained within a porous container. Wade, U.S. Pat. No. 3,224,586, discloses a bag assemblage usable for removing impurities from a given quantity of liquid, and is especially directed to the problem of removing radioactive isotopes from water using ion exchange resins. The foregoing devices, however, do not contemplate the use of activated carbon nor do they address themselves to the inhibition of particulate migration.
Additionally, various devices have been disclosed for treating water with either granular active carbon or granular activated charcoal as it is variously known. For example, Young, U.S. Pat. No. 1,208,882 relates to improvements in canvas domestic water bags consisting of a device fitted to the bag and consisting of a container to hold charcoal wherein the charcoal is held in the container by a sponge or other suitable porous stopper-like closure. Rabjon, U.S. Pat. No. 2,435,510, discloses a filter cartridge for purifying ordinary hydrant water for drinking purposes. Simpson, et al., U.S. Pat. No. 2,633,990, discloses a cartridge filtration device using activated carbon or a diatomaceous earth pretreated with gaseous chlorine or other sterilizing agent. Sanzenbacher, U.S. Pat. No. 3,392,837 discloses another water conditioning unit employing activated charcoal in conjunction with other substances such as silver and water softening additives for the ultimate purification of the water.
A major problem associated with porous devices using particulate matter for purifying the water is the migration of the particulate matter from the device either along with or into the purified water. Several attempts have been made to reduce this problem. Gudmundsen, U.S. Pat. No. 2,117,091, sets forth the use of fine grain zeolite and the prevention of fines migration by the use of a closely woven fabric through which fluid may pass and at the same time retain the exchanging particles. Dunn, et al., U.S. Pat. No. 3,225,932, employs a protective shield comprising an arrangement of a perforated or woven fabric bag with an outlet tube to form a tight seal for preventing the escape of particulate carbon. Teeple et al., U.S. Pat. No. 3,715,035 discloses a high capacity portable water purifier employing a sediment trap that will filter out particulate matter including the active charcoal and deionizing resin utilized in the device.
The foregoing approaches deal primarily with modification of the porous element of the device in order to prevent passage of particulate matter. By contrast, Andrus, U.S. Pat. No. 2,072,976 suggests a device employing water soluble chemicals which are intended to escape the device and to react with each other or with soluble impurities to form a coagulum. The coagulum containing the impurities is then allowed to settle out of the water or the water is filtered to separate the same. This has the disadvantage, however, of requiring further filtration and separation.
While various solutions of water purification problem have been proposed, they have many disadvantages, among them being overtreatment of the water (i.e., removal of necessary metallic ions), use of cumbersome and expensive devices, and the inability to prevent the fine particles of the purification agent from entering the water during and after treatment.
The present invention now affords a novel means for the prevention of fine particles of the treatment agents from migrating through a container fabricated for the purpose of purifying drinking water. Additionally, this invention now allows for the easy and inexpensive treatment of drinking water to remove certain impurities that adversely affect their organoleptic acceptability.